I'm not quite sure how much drywall mud I'll be using for my upcoming project so I'm planning to buy a box of it. Assuming that I have some left over, is there a technique for not wasting it? Will it last for awhile if I make sure to tie up the bag again and close the box lid? Or should I assume that it'll only last for a short time after I initially open the box.

Also, what's the shelf life for drywall mud? Should I only buy as much as I think I need? Or if I found a good deal, will it keep for awhile (for use with other projects later)?

3 Answers
3

I don't have any experience with boxes, but have quite a bit with the 5-gallon buckets of compound. Without knowing much about how those boxes seal, I'd recommend going with a bucket- the buckets/lids seal air tight which is important for keeping the mud from drying out. The other thing I'd recommend- every time you close the box or bucket, put a piece of plastic sheeting over the top of the mud. This traps the moisture in against the mud, and prolongs its shelf life. The buckets come with a round piece of plastic sheeting on top of the mud-
I just fold it in half (to keep any bits of mud stuck to the plastic from being exposed to air) then when I am done for the day, unfold it, and put it back on top of the mud in the bucket.

I second the bucket recommendation; it'll be about the right consistency when you open it.
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Niall C.♦Oct 25 '10 at 17:00

2

+1 for pressing plastic sheeting down against the mud.
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Alex FeinmanOct 25 '10 at 17:01

1

When I built my son's nursery I bought the 1 gal buckets (I could only work a couple hours a day and had no idea how much mud it would take - answer: ~ 15 gals ) and once I had four collected I bought the 3.5 gal box of premix and divided it up into my buckets. I recently pulled out a bucket of over a year old mud and it was fine with a little water.
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Steve JacksonOct 25 '10 at 18:06

As MarkD mentioned, the 5 gallon buckets are the way to go for ready-mix. They seal up nicely and have a very long shelf life. If I pull out an old one, I'll usually add a bit of water, mix it up a bit, and it'll be fine.

Just to cover another option - you also have the dry unmixed compound that comes in bags. These are really an entirely different beast from the pre-mix buckets though:

They tend to absorb moisture from the air, so shelf life is limited to maybe a couple months before they get "clumpy".

They dry much more quickly (20 - 90 minutes depending on the variety), which is nice if you want to put on multiple coats in a day.

They dry much harder - the faster they dry, the harder it will be - which is nice for filling low spots or base coats, but terrible for sanding.

Once they start to dry, it's over - you can't add water to soften them up. So you only mix up as much as you can put on in 15-30 minutes or so. If it starts to set in your mud tray it's too late - throw it out and mix up some more.

For a first time mudding, I'd recommend going with a pre-mixed compound. One has enough to worry about those first (20) times mudding- adding mixing the powder to the right consistency (without even knowing what the right consistency is) seems like a recipe for frustration. (all too much experience with frustration here. ;) )
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MarkDOct 25 '10 at 18:06

1

@MarkD - I'd agree with you 100% there. Just thought I'd add some info on the dry mix options for others who might wonder about this later.
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Eric PetroeljeOct 25 '10 at 18:36

In addition to pressing the plastic sheeting over the surface as @MarkD suggests, make sure you also pack it down flat before doing so. Take the time to scrape all the extra mud off the sides of the box/bucket and smooth out the top surface. This will minimize the area exposed and keep you from getting crusties flaking off the sides of the container into your good mud.